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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Atraminių sienų skerspjūvio mažėjimas veikiant nepalankiems aplinkos poveikiams / Reduction of cross–section of retaining walls under the influence of negative environmental impacts

Pupelis, Vytas 16 June 2010 (has links)
Žemių užtvankų žemutinio bjefo atraminės sienos (toliau – AS) yra veikiamos nepalankių klimatinių poveikių, vandens, grunto slėgio ir kt. apkrovų. Veikiant agresyvioms aplinkoms ir apkrovoms atsiranda pažaidos, kurios ardo atraminę sieną bei mažina konstrukcijos laikomąją galią. Darbo tikslas – įvertinti nepalankių aplinkos poveikių įtaką atraminių sienų skerspjūvio sumažėjimui. 2007–2010 metais mokslinių ekspedicijų metu įvertinta 21 hidromazgo atraminių sienų būklė. Apžiūrėtos Kauno, Panevėžio, Utenos ir Marijampolės apskričių hidromazgų atraminės sienos, fiksuotos svarbiausios pažaidos. Detaliau ištirta Antanavo hidromazgo atraminė siena, įvertintas sienos skerspjūvio sumažėjimas dėl nepalankių aplinkos poveikių. Pagal tyrimų duomenis pasiūlyti pažaidų, mažinančių atraminių sienų skerspjūvį, remonto būdai. / Retaining walls of lower head–water of ground dams are influenced by negative climatic impacts, water, ground pressure and other loads. Upon the effect of aggressive environment and loads, deteriorations occur destroying the retaining wall as well as reducing the bearing capacity of the constructions. The aim of the work is to evaluate reduction of cross–section of retaining walls as a result of negative environmental impacts. Through the period 2007–2010 on scientific expeditions the condition of retaining walls of 21 hydroshemes was assessed. Retaining walls of hydroschemes in the counties of Kaunas, Panevezys, Utena and Marijampole have been examined, the most significant deteriorations were fixed. Retaining wall in Antanavas hydropower station was examined in detail; reduction of cross–section of retaining wall due to the influence of negative environmental impacts was assessed.
72

Estruturas de contenção reforçadas com geossintéticos / Reinforced retaining structures with geosynthetics

Pedroso, Emerson Oliveira 06 October 2000 (has links)
Este trabalho apresenta a construção e instrumentação de uma estrutura de contenção reforçada com geotêxtil, com 4,0 m de altura, construída na cidade de Nova Odessa-SP. A instrumentação consistiu em medir os deslocamentos horizontais e verticais com barras de aço e placas magnéticas, respectivamente. Além disso, foram realizadas simulações numéricas para comparar os resultados medidos e simulados do protótipo e avaliar o comportamento da estrutura para alguns tipos de solo, rigidez da inclusão e arranjos das inclusões. Pode-se concluir que os resultados medidos e simulados estão concordantes. Através das análises paramétricas concluiu-se que aumentando-se a rigidez do solo reduz-se os deslocamentos horizontais da estrutura. Com o aumento na rigidez da inclusão obtém-se menores deslocamentos, no entanto, em solos muito rígidos esta redução é pouco significativa. As estruturas com maior número de reforços reduzem as tensões em cada inclusão e diminuem os deslocamentos horizontais da estrutura. As forças de tração máximas, mobilizadas nas inclusões, são maiores para solos menos rígidos. Alguns resultados de obras instrumentadas, encontrados na literatura, são apresentados e comparados com os medidos e simulados. Destas comparações concluiu-se que o tipo de solo é o fator que mais influencia no desempenho de estruturas de contenção reforçadas com geossintéticos / This work presents the construction and instrumentation of a geotextile reinforced retaining structure, with 4,0 m height, built in the city of Nova Odessa-SP. The instrumentation consisted of measuring the horizontal and vertical displacements with steel bars and magnetic plates, respectively. Numeric simulations were accomplished to compare the measured and simulated results of the prototype and to evaluate the behavior of the structure for some soil types, reinforcement rigidity and different reinforcement layout. It was concluded that the measured and simulated results are in good agreement. The parametric analyses showed that the amount of horizontal displacements of the structure are reduced when the rigidity of the soil increases. Although smaller displacements are obtained when the rigidity of the inclusion is increased, in very rigid soils this reduction is not very significant. Structures with larger number of reinforcements reduce the stresses in each inclusion, decreasing the horizontal displacements of the structure. The maximum tensile forces mobilized in the inclusions, are larger for less rigid soils. Some case record results documented in the literature are presented and compared with the measured and simulated results obtained in this work. These comparisons allowed to conclude that the soil type is the most relevant factor in the performance of reinforced retaining structure with geosynthetics
73

Att trivas på sitt arbete : En kvalitativ studie om soldater och officerares upplevelser av arbetsplatsen

Öhman, Julia January 2019 (has links)
A job is not only an economic factor for the individual; the work also has a great impact on the individual's well-being. It is therefore a prerequisite for employees to be happy at work, which places demands on the workplace. The purpose of the study is to investigate what soldiers and officers have for experiences of job satisfaction. This is answered by studying a specific company on an aircraft fleet within the Swedish Armed Forces based on these research questions: How do the informants experience their work situation at the company? What difficulties and opportunities can be identified based on the informants' work situation and how can these be understood? The thesis is based on a qualitative method and the empirical data has been collected through interviews with four officers and four soldiers. The theoretical framework is based on previous research on employees and job satisfaction, Herzberg's two-stage model and Karasek and Theorell's demand- control-support model. The results of the study show that both the soldiers and the officers feel that the high workload of the company causes the work situation to be perceived as worse. The informants also feel that they do not get paid for the work they do, that the workload prevents them from developing, that everyone does not get feedback in the way they had wanted and that the goals and requirements that are set for the function sometimes are too unclear. Furthermore, the results show that the officers and soldiers generally agree on how well-being is generally experienced at the company. The main difference between the soldiers and the officers is that the soldiers feel that their work situation is affected for the worse because they do not have the same powers to make decisions within the organization. What the informants especially feel is contributing to a more pleasant work situation is the good cohesion between the employees. The informants feel that their work situation is affected to a lesser extent by a number of aspects, but nevertheless the majority of the informants want to continue working at the company.
74

A finite difference soil-structure interaction study of a section of the Bonneville Navigation Lock buttress diaphragm wall utilizing pressuremeter test results

McCormack, Thomas C. 01 January 1987 (has links)
The P-y curve, used in current practice as an efficient Iine-load vs. soi displacement model for input into the finite difference method of laterally loaded pile analysis, is extended in this study for use with cohesionless soils in diaphragm wall analysis on the Personal Computer with the BMCOL7 program. An analogous W-y curve is proposed, an elastic-plastic model with line-load limits developed from classical earth-pressure theories. A new formula for predicting a horizontal walI modulus for cohesionless soiIs from the pressuremeter modulus is developed for use in predicting the displacements on the W-y curves. The resulting modulus values are shown to yield reasonable displacements values. A new procedure for modeling preloaded tie-back anchors and staged excavation for diaphragm walIs was developed, utiIizing multiple computer runs, updated the W-y curves, and superposition of deflections. These new developments were applied to a parametric study of a deflection-critical section of the new Bonnevilie Nav-Lock Buttress Diaphragm Wall, for which extensive high-quality pressuremeter test results were available. Deflection curves of the wall are presented, showing the effect of variations in anchor preload, walI cracking, anchor slip, at-rest pressure, and soiI modulus. The results indicate that preloading will reduce wall deflections by at least 4-fold, but that wall cracking can potentially double deflections. Safety factors against passive soil failure were determined to be about 5 at anchor preload, and more than 40 after fulI excavation.
75

Behaviour and analysis of embedded cantilever wall on a slope

Ong, Chin Chai January 2007 (has links)
[Truncated abstract] The feasibility of using interlocked light gauge sheet piles to form a deep cross-sectional wall embedded in a residual slope or with a berm support is explored. This thesis compares the performance of a large section modulus sheet pile wall as an alternative to a concrete diaphragm wall, acting as an embedded cantilever wall on a slope (ECWS) by means of experimental centrifuge tests, numerical models and analytical methods. Abaqus (Hibbitt, Karlsson and Sorensen Inc, 1997) was used to conduct extensive numerical trials on the structural performance of the sheet pile wall model prior to the actual physical testing. The Abaqus results showed that the integrity of the interlock and reduced modulus action (RMA) due to slippage along the interlocked joint did not cause premature buckling of the thin wall even at the ultimate load. Further, a comparative study using centrifuge tests on 1:30 scaled models and Plaxis analysis demonstrated that under the worst condition with high water table, the rigid sheet pile wall of 1.32 m cross-sectional width carried a higher ultimate surcharge load with a much lower top of wall deflection, compared to a more flexible 0.6 m thick cracked concrete diaphragm wall. The analysis of the wall/soil/slope interactions for an ECWS involves many inter-dependent variables in addition to the complications of considering an adjacent slope or a berm support. It is difficult for existing analytical approaches to take all these factors into account, and some form of numerical analysis, calibrated through field data and results from centrifuge model tests is necessary. From the observations of the centrifuge tests and finite element analysis, major assumptions about the failure of a stiff ECWS in a rotational mode were deduced and adopted in the proposed limiting equilibrium method (Leq). The plane strain Leq ECWS Abstract ii analysis is based on the framework of minimum upper bound limiting equilibrium with planar failure planes and a Mohr-Coulomb soil model. As compared to the traditional limit equilibrium analysis, the Leq method is a fully coupled analysis using the shear strength reduction technique (SSR). New formulations are proposed for the development of horizontal active and passive pressure distributions based on the experimental and FE models. The proposed active pressure profile used is derived by combining the Coulomb and Krey method, and empirically back-figured to curve-fit the centrifuge tests by Morris (2005). The proposed passive pressure profile of a rigid rotational wall in failure is adjusted to allow for an adjacent slope or berm support through a presumed elasto-plastic deformation instead of a linear rigid translation of the passive wedge. ... A parametric study was later undertaken using the Leq method to develop a series of non-dimensionalised graphs to study and draw summarised conclusions on the behaviour of the ECWS. The final conclusions on the comparative study of the centrifuge tests, Plaxis and Leq analyses demonstrated that the alternative light gauge steel sheet pile performed very well as an ECWS. A key factor in the performance of the sheet pile wall was attributed to the large 1.32 m cross-sectional width of the interlocked sections. This provided high bending stiffness and high moment stability from shear stresses acting on the back and front faces of the wall.
76

Employer Branding in Human Resource Management : The Importance of Recruiting and Retaining Employees

Öster, Hedvig, Jonze, Johanna January 2013 (has links)
Problem: Companies are facing problems concerning the attraction and retention of talented employees, due to the shortage of individuals with competence. Employer Branding is a relatively new concept that can function as an instrument for firms to position themselves as an employer, in order to attract and retain wanted employees. Purpose: The purpose of this thesis is to examine the field of Employer Branding in the context of recruitment and retaining. The study examines the questions of how and why Employer Branding is implemented in firms and what role such implementation plays in Human Resource Management, in the context of recruitment and retaining processes. Methodology: This study has been made with a qualitative approach, with a descriptive and exploratory purpose a case study approach. Data has primarily been collected through interviews at five different companies with knowledge within the area of Employer Branding. Findings: Employer Branding can be utilized both externally to attract potential employees, and internally to increase commitment and loyalty among current employees. In the context of recruitment, Employer Branding can make the process more effective. For the Employer Brand to be trustworthy and successful the consistency between the internal values and the external image is vital.
77

Comparison Of Analysis Methods Of Embedded Retaining Walls

Harmandar, Serkan 01 January 2007 (has links) (PDF)
ABSTRACT COMPARISON OF ANALYSIS METHODS OF EMBEDDED RETAINING WALLS HARMANDAR, Serkan M.S., Department of Civil Engineering Supervisor : Prof. Dr. Yener &Ouml / zkan Co -Supervisor : Dr. Oguz &Ccedil / aliSan December 2006, 123 pages In this study a single-propped embedded retaining wall supporting a cohesionless soil is investigated by four approaches, namely limit equilibrium, subgrade reaction, pseudo-finite element and finite element methods. Structural forces, such as strut loads, wall shear forces, bending moments are calculated by each method and results are compared. The analyses are carried for for three values of internal friction angle of soil / 30o, 35o, and 40o. Effects of modulus of soil elasticity of the backfill and wall stiffness on structural forces are investigated by using different values for these parameters. It is found that, in those of obtained by, limit equilibrium approach results in embedment depth greater than other methods. Minimum strut loads for the same soil and structure parameters are obtained by limit equilibrium method. An increase of Young&rsquo / s modulus of the soil results in decrease of the strut loads.
78

Comparison Of Factor Of Safety Obtained From Limit Equilibrium Methods With Strength Reduction Factors In Finite Element Modeling

Engin, Volkan 01 February 2012 (has links) (PDF)
Designing with Limit Equilibrium Methods involve a factor of safety (FS) in order to maintain the stability and to keep the resisting structure away from limit state on the safe side. Finite Element Program (such as Plaxis) on the other hand, instead of an FS, reduces the shear strength of the soil by introducing a reduction factor that is applied to tan
79

Passive Earth Pressure Coefficients And There Applications In The Uplift Capacity Of Anchors

Nayak, Sitaram 04 1900 (has links)
The problem of passive earth pressure is one of the important topics in Geotechnical engineering. At attempt is made in this thesis to generate passive earth pressure coefficients for general c-Φ soils using logarithmic spiral failure surface by limit equilibrium approach. Method of slices for the determination of passive force in c-Φsoils is presented and the method is extended to a typical problem of two layered soil system. The application of passive earth pressure coefficients has been demonstrated for pullout capacity of inclined strip anchors in sloping ground. A semi-empirical approach for the determination of displacement-related passive earth pressure is presented. The thesis is organized in seven chapters. In Ch.2, a brief summary of relevant literature is presented along with the scope of the thesis. In Ch. 3, limit equilibrium approach for the determination of the passive earth pressure in soils is presented. The passive earth pressure coefficients are developed for δ/Φ= - 1, - ¾ , -2/3, - ½, 0, ½, ¾ 1; ψ = -60º, -45º, -30º, -20º, -10º, 0º,10º,20º,30º and 45º; i= -30º, -20º, -10º,0º,10º,20º and 30º where δ is the wall friction angle, Φ is the angle of internal friction, Ψ is the inclination of the wall with the vertical and i is the ground inclination with the horizontal. Ch.4 deals with the method of slices. Satisfying all the three equilibrium conditions and using interstice friction as a variable, passive earth pressure coefficients are obtained for soils. Extension of the method to a two layered soil system is demonstrated by an illustrative example. A generalised approach for the determination of uplift capacity of inclined strip anchors in sloping ground subjected to surcharge is presented in Ch. 5. Expressions are provided for the determination of pullout capacity of deep anchors. Displacement-related passive earth pressure is discussed in Ch. 6. Using the earlier experimental observations on the passive earth pressure measurements with displacements, expressions have been fitted for the determination of displacement-related passive earth pressure for the three modes of rigid body movements viz., translation, rotation about the top and rotation about the bottom. The conclusions drawn from the present investigations are listed in Ch 7. (Pl see the original document for abstract)
80

A behavioral study of gabion retaining walls

Sublette, William Robert January 1979 (has links)
No description available.

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